Polishing apparatus



United States Patent 3,499,250 POLISHING APPARATUS Elmer W. Jensen,Mount Vernon, N.Y., and Hans R.

Jacobsen, Norwalk, C0nn., assignors to Geoscience InstrumentsCorporation, Mount Vernon, N.Y., a corporation of New YorkContinuation-impart of application Ser. No. 562,757,

July 5, 1966. This application Apr. 7, 1967, Ser.

Int. Cl. B24b 7/00, 9/00, 11/00 U.S. Cl. 51109 7 Claims ABSTRACT OF THEDISCLOSURE An organization for polishing bulk materials such as glass,stone, metals or the like, includes layers of a poromeric material suchas Corfam and sponge rubber to produce an internal self-cleaning, wastematerial expelling mechanism.

This invention relates to apparatus for effecting polishing operations.The application is a continuation-in-part of my pending application Ser.No. 562,757, filed July 5, 1966.

There is extensive present applications for materials to impart a highlypolished finish to glass, Corning Ware (a trademark of the Corning GlassWorks for a ceramic composition), stone and the like. To effect suchfinishing, a polishing cloth is typically used in conjunction with anabrasive polishing slurry.

However, prior art compositions which have heretofore embodied polishingcloths have been characterized by one or more of the followingdeficiencies: (l) temperature sensitivity, and therefore instability athigh polishing rates; (2) heterogeneous consistency; (3) a propensity topick up and retain foreign elements; (4) poor wear characteristicsrequiring frequent replacement; (5) variations from sample to sample;(6) the characteristic of being impermeable and thereby preventing apolishing slurry from reaching all surface areas of a work materialbeing operated upon; (7) relatively little tensile strength, therebybeing subject to distortion; and (8) a resistance to bonding therebybeing difiicult to affix to cooperating compositions and/or a lappingplate.

To expand upon item (3) above, a polishing cloth for finishing bulkmaterials must be self-cleaning, i.e., must have an internal mechanismto expel large slurry or waste particles thrown off by the subjectmaterial when materials of relatively large size, such as thoseillustratively specified above, are polished. Failure to expel theseundesirable particles will cause scratching, rather than polishing ofthe workpiece surface, and also results in destruction of the polishingmaterial when the requisite high polishing speeds are employed.

It is therefore an object of the present invention to provide animproved apparatus for polishing workpieces.

More specifically, an object of the present invention is the provisionof a resilient, homogeneous polishing organization which is porous,relatively insensitive to temperature, and which is self-cleaning, i.e.,which expels undesirable waste products.

These and other objects of the present invention are realized in aspecific illustrative polishing organization which comprises a layer ofCorfam (a trademark of the Du Pont Corporation for poromeric material,i.e.," a microporous and permeable coriaceous nonwoven sheet comprisinga urethane polymer base reinforced with polyester), having a pluralityof apertures therethrough. A layer of sponge rubber is disposed betweenthe Corfam material and a polishing mechanism such as a lapping orpolishing plate.

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The active Corfam surface is made flat, and is adapted to polishworkpieces brought in frictional contact'therewith. A Corfam compositionincluding the above-mentioned apertures cooperates with the spongerubber layer to impart a living texture, i.e., the properties ofcompressibility and resiliency to the composite polishing organization.Accordingly, the Corfam composition expels rather than retains slurryparticles and waste materials from the workpiece coming in contacttherewith.

A complete understanding of the present invention and of the above andother objects thereof may be gained from a consideration of anillustrative embodiment thereof depicted in the accompanying drawing.

Referring now to the drawing, there is shown in elevation form anillustrative polishing organization which embodies the principles of thepresent invention. The arrangement includes a layer of Corfam 20 havinga layer,

of Buna-N rubber 35 affixed thereto via an adhesive 30. The Corfam 20has a plurality of apertures 25 therethrough from its active upperpolishing surface to, and optionally through the Buna-N rubber 35. Thefunction of these apertures 25 is presented hereinbelow. A pressuresensitive clean release adhesive 40 is employed to bond the Buna-Nrubber 35 to a layer of sponge rubber 50. It is noted that otherporomeric materials, as well as other compositions embodying theattributes of Corfam described herein may be employed in place of theCorfam 20.

The Corfam 20 is fabricated such that the active, or upper surfacethereof exhibits the requisite flatness for a particular polishingoperation (assuming that a fiat surface is desired for a workpiece). Toeffect such polishing, the layer 20 is urged into bearing pressurecontact with a material 15 to be polished, with such elements 15typically comprising, for example, glass, stone, metal surfaces, CorningWare or the like. The polishing is advantageously performed in a slurryenvironment, with a slurry being supplied by a source 60 thereof via anozzle 61 The Corfam material 20 is very porous, and hence the slurry istranslated by the layer 20 to all portions of the surface of the element15 thereby effecting uniform polishing. Also, the Corfam material 20 isessentially insensitive to temperature, at least in the temperaturerange of interest for polishing operations. Accordingly, polish ing maybe accompli hed at the high rates of speed required for relatively largeworkpieces. Moreover, the Corfam 20 is homogeneous, and may befabricated in relatively large quantities to produce many uniformpolishing elements without material variation from sample to sample.

With large, bulk work elements 15 as illustratively enumerated above,prior art polishing cloths have worn very rapidly. In such polishingapplications, the large, hard waste particles from the subjectworkpiece, and large abrasive particles in the slurry, become embeddedin the cloth. Then when the cloth rubs against the workpiece at thecharacteristic high rate of speed, the trapped particles operate torapidly destroy the polishing cloth.

According to one aspect of the present invention, the Corfam 20 with itsassociated axial apertures 25, acting in cooperation with the spongerubber 50, impart a living texture to the cloth. That is, when thepolishing surface is depressed by an applied pressure, it will springback when the pressure is removed. Further, such a depression maytraverse across the polishing surface. These qualities have been foundto impart a self-cleaning property to the composite polishing cloth,i.e., to enable it to expel any waste particles with which it comes incontact. This, in turn, imparts a long service life to the polishingorganization, which is not self-consuming when effecting its polishingfunction.

As an additional feature, the active, upper surface of the Corfam layer20 can be treated or impregnated for special polishing operations. Suchtreatment may comprise, for example, brushing, knapping, skiving ortexturing the Corfam surface to increase the active polishing area, orcalendaring the surface to increase its flat- By way of functionaloperation, the composite laminated polishing operation 20-2530354045-50is urged in rotational bearing contact by a lapping plate 55 or the likein the presence of slurry supplied bythe source 60. The resultingfrictional interface between the upper surface of the Corfam 20 and thework-piece imparts the desired polished surface to the member 15. Duringsuch polishing, the characteristic living texture for the compositeorganization is effective to expel all undesirable particles to ensure aprolonged life for the Corfam material 20.

It is noted at this point that the clean release adhesive 40, and theBuna-N rubber 30 to which such an adhesive readily bonds, are employedto facilitate the removal of the Corfam from the sponge rubber 50 at thetermination of useful life for the active layer 20. If desired, thesponge rubber 50 may be affixed to the Corfam 20, either directly curedtherein or attached by any of the well known adhesives therefor.

It is to be understood that the above-described method and organizationare only illustrative of the application of the principles of thepresent invention. Numerous other arrangements and modes of operationmay be devised by those skilled in the art without departing from thespirit and scope of the invention.

What is claimed is:

1. In combination in a polishing apparatus, a poromeric material havinga first operative polishing surface and an oppositely disposed secondsurface, a plurality of vacated apertures formed in said poromericmaterial and included in said first poromeric surface and aligned towardsaid second surface, and a layer of compressible material afiixed tosaid second surface of said poromeric material.

2. The combination as in claim 1 wherein said compressible materialcomprises sponge rubber.

3. The combination as in claim 1 further comprising a layer of Buna-Nrubber interposed between said second surface of said poromeric materialand said compressible material.

4. The combination as in claim 3 further comprising a pressure sensitiveclean release adhesive interposed between said Buna-N rubber and saidsponge rubber.

5. In combination in a polishing organization, a poromeric materialhaving a plurality of vacated, formed, apertures in said poromericmaterial separate from the natural properties of said poromericmaterial, and means for urging work pieces to be polished into :bearingcontact with said poromeric material.

6. The combination as in claim 5 further comprising a layer ofcompressible material interposed between said poromeric material andsaid urging means.

7. The combination as in claim 6 wherein said compressible materialcomprises sponge rubber.

References Cited UNITED STATES PATENTS 671,130 4/1901 Darden 51401804,853 11/ 1905 Ireson. 1,923,719 8/1933 Fuller 5l30'1 2,644,280 7/1953ONeil.

OTHER REFERENCES Boot and Shoe Recorder Oct. 1, 1963, article titled TheStory of Corfam, pp. 1 and 2 thereof.

HAROLD D. WHITEHEAD, Primary Examiner US. Cl. X.R. 51-401; 161160

